CJD Discovery - Mice Cured In 'Specatularly Succesful Experiment'
BBC News - Health
A chemical that experts believe may be able to treat the brain disease CJD has produced spectacularly successful results in mice.
A team from the Institute for Animal Health in Edinburgh inoculated mice that had been infected with scrapie - a disease of the brain similar to CJD - with the chemical pentosan polysulphate (PS).
Animals injected with one milligram of PS appeared to be completely protected against the scrapie. They died from unrelated causes between 500 and 707 days after they were "inoculated" with the drug.
Mice who received no PS died of scrapie within 428 days.
The incubation period for scrapie was increased by up to 66% for doses of PS as small as 250 micrograms.
The researchers say further studies are now needed to test whether PS can reduce the risk of CJD.
Dr Moira Bruce, head of pathology at the institute, said the previous research had shown PS to be effective in treating scrapie, but not in such small, single doses.
The Edinburgh research is also the first time that animals have been successfully treated after being infected. Previously, they were inoculated before being infected with the disease.
Dr Bruce said: "This research shows that a very small dose can produce really quite a dramatic effect if you get the time right."
Dr Bruce warned, however, that much more work was needed before the drug was used on humans. She said there would be problems identifying which people were carrying the CJD infection soon enough to ensure PS could work.
Spongy texture
Thirty-five people in the UK have been diagnosed as suffering from new variant CJD since scientists said in March 1996 that they had evidence it could be contracted by eating beef from animals suffering from BSE, or mad cow disease.
CJD, like BSE and scrapie, causes the brain to develop a spongy texture known as spongiform encephalopathy.
At present, there is no treatment to slow or halt nv-CJD, and the diagnosis is usually made when patients are terminally ill.
During the long incubation period when there are no symptoms, there is a risk that the infection may be transferred by blood transfusion, treatment with blood products, transplantation or reuse of surgical instruments.
PS is already licensed in the US for the treatment of a form of cystitis.
Microbiologist Dr Stephen Dealler, of Burnley General Hospital, is working on a treatment for CJD in humans.
He said the Edinburgh research was "very exciting".
"Pentosan does not just prevent the disease from progressing in animals, it actually gets rid of it," he said.
"The potential importance of this drug to humans cannot be underestimated."
Drug Offers Hope On CJD/BSE Front
By Alan MacDermid
Scientists have found that a drug might be effective in curbing or protecting against the human form of so-called mad cow disease.
Researchers at the Institute for Animal Health in Edinburgh called for further trials of the drug, pentosan polysulphate, which is used in the US to treat cystitis.
They tested it on mice seven hours after they had been infected with scrapie, a sheep-borne form of transmissible spongiform encephalopathy thought to be the origin of Creutzfeldt-Jakob Disease and its human equivalent, new variant CJD.
Some mice survived longer than mice that did not get the drug; others did not succumb to the disease at all.
The findings are reported today in the Lancet, and last night it emerged that scientists advising the Government on CJD will consider the use of pentosan on Monday. The Spongiform Encephalopathy Advisory Committee will look at all the evidence and may then make a recommendation to Ministers.
Thirty-five people in Britain have been diagnosed as having the invariably fatal nvCJD since scientists said in 1996 that it could be contracted by eating beef infected by mad cow disease.
The extent of the future problem is unclear because of the long incubation period associated with the disease.
The mice were a special breed genetically engineered to be susceptible to the sheep disease.
The researchers found that 250 micrograms of pentosan increased the average incubation period of one scrapie strain by up to 66%.
A milligram of pentosan protected mice completely from another strain.
The Lancet report states: "This represents at least a hundred-fold reduction in the sensitivity of these mice to infection. Although direct testing of the efficacy of pentosan polysulphate in reducing susceptibility to nvCJD is not possible, further animal studies are essential to examine the possible use of the drug for risk reduction."
One of the Edinburgh researchers, Dr Moira Bruce, said yesterday: "We are at a fairly early stage in considering a practical application. What we have shown is that a single low dose given very shortly after exposure can extend the incubation period and in some cases protect the animals.
"We don't know enough about the action of this drug yet to the extent of suggesting how it might be used. The problem with CJD is that individuals are normally infected long before they develop any clinical indications, and the effect of the drug is in the early stages. So we would have the problem of knowing when to give it. However there have been other animal studies in which large doses were given prior to infection and proved effective.
"We do not know if it would be effective in humans, we aren't sure about side-effects, and we have not tried it on BSE itself."
Diseases such as CJD are thought to spread by a rogue form of protein turning other proteins "bad" in a chain reaction. Pentosan latches on to the proteins, called prions, and stops them affecting their neighbours.
Dr Stephen Dealler, who has reviewed several studies of pentosan's effects, said: "This is a nettle that needs to be grasped. We may actually have a drug which can prevent humans becoming infected. The Government must do something about it immediately." - Jan 8